Torque transmission member

ABSTRACT

In a torque control device a speed control valve is used for controlling the number of revolutions of an air motor for applying the torque. When the torque output is to be increased, the valve opens and increases the air pressure to the air motor. The speed control device includes an adjusting screw for regulating a spring so that the valve opening is regulated and the number of revolutions of the air motor can be selectively controlled at no load or light load.

United States Patent Tsujiet al.

[ 51 Aug. 15, 1972 [54] TORQUE TRANSMISSION MEMBER [72] Inventors: ShuTsuji, 21-5, 3, Honda Kokubunji-cho; Hiroshi Tsuji, 1318-8, Shimofuda,both of Chofu-shi, Tokyo, Japan [22] Filed: Jan. 6, 1970 [21] App1.No.:880

Related US. Application Data [62] Division of Ser. No. 760,279, Sept.17, 1968,

Pat. No. 3,543,902.

[30] Foreign Application Priority Data Feb. 13, 1968 Japan ..43/9039June 5, 1968 Japan ..43/38500 June 5, 1968 Japan ..43/38501 [52] US. Cl...l37/523, 137/513.5, 137/538 [51] Int. Cl ..Fl6k 17/00 [58] Field ofSearch 130 5135, 5'23 [56] References Cited UNITED STATES PATENTS1,523,981 l/1925 Harris ..137/523 X 1,806,462 5/1931 Hopkins ..137/523 X2,051,100 8/1936 Nelson .;.....137/523 3,200,830 8/1965 Moyer et a1..l37/5l3.5 X 3,448,765 6/1969 McKinney ..l37/513.5

Primary ExaminerRobert G. Nilson Assistant Examiner-David J. ZobkiwAttorney-McGlew and Toren [5 7] ABSTRACT In a torque control device aspeed control valve is used for controlling the number of revolutions ofan air motor for applying the torque. When the torque output is to beincreased, the valve opens and increases the air pressure to the airmotor. The speed control'device includes an adjusting screw forregulating a spring so that the valve opening is regulated and thenumber of revolutions of the air motor can be selectively controlled atno load or light load.

' 1 Claim, l4 Drawing; Figures Patented Aug. 15, 1972 5 sheets-sheet 1 wwmhw M a 2 a 2 lllll SHU TsutYl @HIROSHI T58 51 ATTORNEYS Patented Aug.15, 1972 3,683,959

5 Sheets-Sheet 2 ATTORNEYS Patented Aug. 15, 1972 3,683,959

5 Sheets-Sheet 5 E INVENTORS s u u Ts u S maps" I 1" U I ATTORNEY IPatented Aug. 15, 1972 3,683,959

5 Sheets-Sheet 5 J6 2 /JJ J4 J7 T I out mi forgue T n:num1 eYoT vevoluhoINVENTORS ATTORNEY$ I TORQUE TRANSMISSION MEMBER This is a division ofapplication Ser. No. 760,279, filed Sept. 17,'1968, now US. Pat. No.3,543,902 issued Dec. 1, 1970. I

This invention relates to a torque transmission system, including atorque control device as well as a torque cut-off device.

The torque transmission system of a power type, using an electric motoror air motor and used as a clamping tool for bolts and nuts or screwsand the like, has been hitherto contrived in several kinds, however, ithas been difficult to keep the clamped torque accurately constant.

Also, in usual torque transmission systems, several methods for cuttingoff the torque have been contrived to detect the value of torque and tomaintain it or to add a constant force, when it reached a certain value.However, in these systems, wherein the torque is detected and the powersources, for instance, an electric source for an electric motor, an airsource for an air motor and an oil pressure source for an oil pressuremotor, are cut off, it is feared that a large torque is generatedtemporarily and predetermined torque value is exceeded due to largeinertia force of the power source, when the output portion is suddenlystopped.

In a system for cutting otf the torque, a clutch and its cut-offmechanism must be included in the rotary portion, thus the constructionbecomes inevitably complicated and has disadvantages in that wearingportions and the like are increased, because the off and on action ofthe clutch are operated from the outside.

Therefore, the object of the present invention is to provide a torquetransmission system having a torque control device, which enables moreaccurate controlling of the transmitted torque for clamping tools andthelike.

The present invention has also as one of its objects to eliminate thedisadvantages of usual torque cut-off devices. And, such an object hasbeen attained by adopting a cut-off system for torque transmission whichreleases the locking of stopped portion by means of planetary gears.

The present invention will be explained in detail in conjunction withthe accompanying drawings, as follOWS;

In the drawings:

FIG. 1 is a sectional view, showing an embodiment of a torquetransmission system according to the present invention;

FIG. 2 is a diagrammatic illustration of the main parts of the torquetransmission system according to the present invention, when the systemis applied to a power type bolt clamping tool;

FIGS. 3a and 3b show the principle of a torque control device in thetorque transmission system of the present invention;

FIG. 4 is a graph showing the relationship between the rotary angle ofthe output shaft as well as the transmitted torque and the rotary angleof the input shaft of the torque control device;

FIG. 5 shows an example of a torque control device having a cut-offdevice in the torque transmission system embodying the presentinvention;

FIG. 6 is a transverse section of the planetary gears portion in FIG. 5;

FIG. 7 is a view, similar to FIG. 5, showing the moved state of thecut-off device in FIG. 5;

FIG. 8 is a diagrammatic illustration of the connection between an usualair motor and its power source;

FIG. 9 is a graph, showing the relationship between the output torqueand the number of revolutions, when the area of valve opening of FIG. 8is varied;

FIG. 10 is a graph, showing the relationship between the pressure behindthe valve and the number of revolutions, when the area of valve openingof FIG. 8 is varied;

FIG. lll is a sectional view, of a speed control valve according to thepresent invention; 1

FIG. 12 is a graph, showing the relationship between the pressure behindthe speed control valve and the area of the valve opening; and

FIG. 13 is a graph, showing the relationship between the output torqueand the number of revolutions of an air motor, when the speed controlvalve of FIG. 11 is used instead of the valve in FIG. 8..

In FIG. ll an embodiment is shown, wherein the torque transmission,according to the present invention is used in a compressed air typeclamping tool for power tightening a screw member, and the explanationof operation thereof now follows.-

Flrst of all, when a trigger 11 is pulled, a stop valve rod 13 is pushedto the right by a lever 12 attached to the trigger with a pin, and bymeans of a tapered por tion 14 of the stop valve rod, a clutch rod l5 ispushed upwardly and locks a ring gear 17 of a planetary gear device I6.Further, the stop valve rod 13 pushes open a ball valve 18 of a stopvalve to introduce compressed air, which will enter a speed controlvalve 20 through a small hole 19 and flow out from narrow clearance ofthe valve to enter a vane-type air motor 2ll. Owing to the narrowclearance of the speed control valve, said vane-type air motor 21 is solimited that its number of revolutions does not increase excessively.

The output passes through the planetary gears device 16 and istransmittedto a torque control portion 22 which includes a togglemechanism. At this time, because the ring gear of the planetary is fixedto the clutch rod, as mentioned above, the torque of the vanetype airmotor will be several times.

The torque is transmitted through a toggle rest 7, the toggles 8arranged on the peripheryand a toggle seat 9, to the output shaft 6 torotate a paired nut. Until the nut rotates on the bolt and seats itselfthereon, the torque is not so much needed and the nut will rotateintact. Once the nut seats on the bolt, the nut clamping torque willsuddenly increase, so that the vane-type air motor rotates very slowlyand the pressure (P) in the motor will rise, accordingly, the speedcontrol valve 20 will open to increase the output torque of vane-typeair motor. When the torque increases further, the axial force of thetoggles 8 will overcome the spring force, which has been set for apredetermined force, and the toggle seat 9 will move slightly to theleft. This slight movement of the toggle seat 9 will rotate a pivotallymounted stopper, 26 by means of a thrust bearing 23.

On the opposite end of the stopper, an adjusting screw 24 is positioned.When the stopper 26 is pivoted by the movement of toggle seat, the lever12 is pushed up on one end by the adjusting screw 24 and a pawl on theother end of the lever 12 will be lowered to disengage the stop valverod 13, which will then be pushed back to the left by the force of stopvalve spring to close the stop valve, thus cutting off the supply ofcompressed air.

Further, due to the movement of the stop valve rod 13, the clutch roddrops downwardly to disengage the locking of the ring gear, so that therotation of the air motor, due to inertia, is not transmitted to theoutput shaft so as not to clamp the nut excessively.

When the trigger 11 is released, the original state is restored, asshown in FIG. 1.

As shown in FIG. 2, the power from a power source A, for instance, anelectric source or a compressed air tank is transmitted to a motor B,for instance, an electric motor including a suitable reduction gear, orto an air motor, through a cut-off portion E, for instance, a switch ora valve. The output torque is transmitted to a bolt clamping tool Dthrough a torque control device C to clamp bolts, nuts, screws and thelike F. When the torque passing through the torque control device Cattains a prescribed torque value, the clamping torque may be easilykept constant in principle, by actuating the cut-off portion E or theclutch between the motor B and the torque control device C as shown inFIG. 2.

But, in this system, it is difficult to keep the clamping torqueaccurately constant, for the following reasons:

1. accuracy of the torque control portion is defective;

2. time lag from the detection of torque to the cutting off the cut-offportion or the delay of operation of the cut-off portion due tomechanical play results in an excessive torque;

3. excessive torque due to inertia energy of motor portion, torquecontrol portion and the like.

The torque control device according to the present invention has beencontrived for the purpose of removing these disadvantages.

Now, the system will be explained with respect to an embodiment shown inthe drawings. In FIGS. 3a and 3b, the torque from an input shaft 31passes from a toggle rest 37 to toggles 38 and is transmitted to atoggle seat 39, then passes into an output shaft 36. For prescribing theoperation torque of the toggles 38, the toggle seat 39 is pushed by aspring 310. And a cut-off portion E is made operative by the movement ofthe toggle seat 39 against the action of the spring 310.

Further, in FIGS. 3 and 3b, two toggles 38 are used, but one or three ormore toggles may be used.

In the torque control device shown in FIG. 3a, when the torque enteringby means of the input shaft 31 does not attain to the prescribed torque(To), the torque passes through the toggles 38 and is transmitted to thetoggle seat 39 and then to the output shaft 36 with the same rotationangle as the input shaft 31 (between A and FIG. in FIGS. 4). Wen thistransmitted torque attains to the prescribed torque (To), the toggles 38begin to stand up and the toggle angle a becomes smaller, as shown inFIG. 3 b, but the output shaft will not rotate until the stopper 318operates, (between B and D in FIG.'4). And the torque during thisinterval becomes smaller than the prescribed torque (To), as describedhereinafter.

The relation between the spring force (P), the transmitted torque andthe toggle angle a is formulated as T=P' r" tana.... (1)

wherer effective radius of toggles, then, the prescribed torque (To) isTo=P:r:tanao...(2)

Namely, when the toggle begins to stand up, or becomes smaller and thetorque (T) becomes smaller than the torque (To).

By means of this system, the torque may be controlled with the accuracyof within 1 percent. Also, the cut-off portion (E) may be operated byutilizing the movement (A x0) of the toggle seat 39. At this time, eventhough time lag and delay of operation are existing, if these areoperating between B and C (A0) in FIG. 4, namely, if A0 0 A0, the outputdoes not rotate and the torque (T) is smaller than the prescribed torque(To). I

Further even though a torque is generated by the inertia of torquecontrol portion, if its kinetic energy (K) "is smaller than thepotential energy (U) of the spring,

which may be absorbed until the end of toggle operation (point D in FIG.4), the transmitted torque (T) does not exceed the prescribed torque(To).

Namely, the kinetic energy (K) is 1 K E J% (3) where, I

J equivalent moment of inertia on the input shaft, to, angular velocityat the time of cutting off on the input shaft. On the other hand, thepotential energy of the spring in consideration of the delay of A0 is(the portion covered by hatching in FIG. 4):

Tdo-= (1 Qua-Ax 4 To satisfy this formula and as shown in FIG. 4, if thedelay is absorbed during the former half (interval B and C) and thecutting ofi is effected and the kinetic energy of motor is absorbedduring the latter half (interval C D), errors due to time lag, delay ofoperation and inertia will not be caused. And, the accuracy of torquedetection for the toggle may be made within 1 percent, so that a torquecontrol device having sufficient accuracy may be obtained.

In the next place, the torque cut-off device will be explained withregard to the embodiment shown in the drawings.

The torque control device shown in FIG. 5 to FIG. 7 may be roughlydivided into five portions, i.e., input portion (A), planetary gearsportion (B), torque detecting portion (C), output portion (D) and torquecutoff portion (E).

The transmitted torque enters from an input flange 41 of (A) portion andis transmitted to a sun gear 42 to drive planetary pinions 43. Theplanetary pinions 43 are fixed with ring gears 44, so that theymake-planetary motions within inner gear thereof to drive a planeta rypin 45, thus the torque is transmitted to a shaft 46.

The torque detecting portion (C) of this drawing is an example of thepreviously described movement of thetoggle, wherein the torque istransmitted from the toggle rest 47 to the toggle seat 49 passingthrough several toggles 48 arranged on the periphery; The toggle seat 49is pushed by means of a spring 410 with a predetermined force, and whenthe transmitted torque attains a predetermined value, the toggle becomesto stand up. The torque transmitted to the toggle seat 49 is thentransmitted to an output flange 411.

The cut-off portion (E) cooperates with the detectingportion (C) usingthe toggle, and the rotation of ring gear (44) of the planetary gearesportion. 43 is stopped by a stop pin 412. The stop pin 412 is locked bymeans of a cut-off lever 414, and when the toggle seat 49 is moved tothe left by the standing up of toggles 48, the locking is released andthe stop pin 412 is disengaged by the force of spring 413, thus the ringgear 44 becomes rotatable (FIG. 7). Since the cut-off lever 414 is urgedagainst the action of the toggle seat 49 by means of a spring 415, ifthe toggle seat 49 is restored for its originalposition, by pushing upthe stop pin 412 again, the stop pin 412 is locked by the cut-off lever414, thus the ring gear 44 is fixed. At this time, a spring 412" ishoused within a head 412' of the stop pin so that the tip of the stoppin 412 may easily enter in the recess of the ring gear 44. v

j Namely, in the present invention, the planetary gears include threerotary motions, i.e.,. the rotation of sun gear 42 the planetary motionof planetary pinions 43 and the rotation of ring gears 44, as shown inFIG. 6, and if two of these are made as input shafts and remaining oneis fixed, then the torque is transmitted with increased or decreasedstate.

FIG. 5 is an example, wherein the sun gear 42 is made as an input shaft,the planetary pinions 43 as an output shaft and the ring gears 44 arefixed. Now, if the fixed portion is released, the torque of input shaftwill not be transmitted to the output portion. If, by releasing the ringgears from the fixed position, the torque is cut-off, the cut-off devicemay be installed on the portion which is being stopped. The constructionof the cut-off portion becomes simple and has no wearing portion, and ifconnected again after cutting off, the operation may be easily effected.FIG. 5 is an example therefor, wherein the movement of the torquedetecting portion (C) in this figure, the standing up of the toggle 48is used, however, not always limited in this method, is transmitted tothe cut-0H lever 414, by which movement the locking of stop pin 412 isreleased, thus the torque may be easily cut off.

And, since the inertia of gears to be fixed may be made small, thetorque due to any shock may be kept to a small value, even thoughtheoutput portion is suddenly stopped.

When the power source is cut-off by a signal from the torque detectingportion at the same time, the input portion may be also stopped withoutcausing any shock, because the input portion may be slowly stopped, evenif the output portion is suddenly stopped.

The timelag until the starting of the cut-off device after the signal issent can be absorbed by the toggle spring as explained hereinbefore.

In the following, a speed control valve for an air motor used for thetorque transmission system of the present inventionwill be explainedabout FIG. 8 to FIG. 13.

FIG. 8 shows diagrammatically the connection of a conventional air motorsystem, wherein compressed air under pressure P is supplied to an airmotor 53 from an original air reservoir 51 under pressure (P,,) througha valve 52 having opened valve area (A), and from the air motor 53, theoutput torque (T), the power having a number of revolutions (n), isobtained.

The characteristics of such an air motor, for instance a vane type airmotor, is that when the opened valve area (A) of the valve 52 isconstant, the number of revolutions (n) will increase as the outputtorque (T) decreases and the number of revolutions (n) will decrease asthe output torque increases, as shown in FIG. 9. Now, in order to makesmaller the number of revolutions (n) for no load (T 0), the openedvalve area (A) is made smaller as, for instance, the lowest curve inFIG. 9, then the output torque (T) becomes considerably smaller comparedwith the maximum torque (To) when the opened valve area (A)'is maximum(A A even though load is borne.

In this manner, if the opened valve area (A) is made smaller for thepurposes of controlling the number of revolutions at no load or lightload, the output torque of air motor will be decreased. It is verytroublesome to control the opened valve area (A) manually in response tothe condition of load.

This invention has been made .to remove such troubles and its essentialpoints consist in a speed control valve of an air motor, characterizedin that the number of revolutions at no load or light load iscontrolled, a throttle valve is arranged on apart of a supply line ofcompressed air so as not to decrease output torque, the throttle valveis made to increase the opened valve area sufficiently due to theincrease of pressure behind the valve, and the minimum opened valve areais assured even though the pressure behind the throttle valve decreasesless than a certain value, further the dimensions of this minimum openedvalve area is made adjustable to control the number of revolutions at noload.

Thereupon, if the speed control valve (FIG. 11) according to thisinvention is used instead of an ordinary throttle valve (52) in FIG. 8,even though the number of revolutions at no load or light load isdecreased, in case the load is increased, the opened valve area (A) isautomatically increased and the maximum torque (To) may be obtained, asshown in FIG. 13.

FIG. 11 is an example of a speed control valve ac- I cording to thepresent invention, wherein the compressed air enters into the valve body54 from below and flows through a passage between the valve body 54 andthe valve 55 and comes out from upper portion, as shown by an arrow. Inthe valve 55, the minimum opened valve area (As) is kept, even thoughthe pressure (P behind the valve is decreased less than a certaindegree.

The characteristics of the speed control valve in FIG. 1 1 is that theopened valve area (A) is varied due to the pressure (P,) behind thevalve, and when the pressure (P becomes maximum (P P the opened valvearea (A) will become maximum (A A,,). And, when the pressure (P behindthe valve decreases less than a certain degree (P P the opened valvearea (A) will be kept constant (A A If such a valve is inserted insteadof the valve 52 of FIG 8, the number of revolutions at no load issuppressed as n n, as shown in FIG. 10, and under these conditions, theload is increased to increase the output torque (T), and when the numberof revolutions decreases the pressure (P,) behind the valve willincrease, and when it attains to P P the valve begins to open and theopened valve area (A) will increase. When the opened valve area (A)becomes larger, the pressure (P,) behind the valve is further increasedto enlarge the opened valve area (A) still more, thus the output torque(T) may become larger until it reaches a necessary value. The maximumthereof may be made so as to reach the same value as that when the valveis fully opened.

When the load decreases under these conditions, the number ofrevolutions (n) of the air motor increases and the pressure (P,) behindthe valve decreases, the opened valve area (A) decreases, as shown inFIG. 12, further the pressure (P,) behind the valve decreases and theopened valve area (A) becomes still smaller until it reaches P P and theopened valve area (A) becomes as A As, thus the number of revolutions(n) may be controlled as n ng. Since the minimum opened valve area.(As)in the speed control valve of FIG. 11 is made variable by means of anadjusting screw (56) against a spring (57), the characteristics of airmotor using the speed control valve according to this invention is thatthe number of revolutions at no load or light load may be controlled atan optional value as shown by full line in FIG. 13, and also the maximumtorque (T may be obtained.

What is claimed is:

l. A speed control valve for use in a supply line delivering a fluidmedium to a fluid driven motor which provides the input power in atorque transmission system, comprising a valve housing, said valvehousing containing an axially extending flow passageway therein with asingle inlet communicating directly into the flow passageway and asingle outlet located at one end of and connected directly to said flowpassageway,

said outlet being spaced in the axial direction of the flow passagewayfrom said inlet, said flow passageway arranged to afford a direct flowof the fluid medium between said inlet and outlet, an axially extendingvalve member movably positioned within the passageway in said housingand extending therein between said inlet and outlet, means for biasingsaid valve member in the axial direction through the flow passagewaytoward said outlet into a position for closing the flow passagewaybetween the inlet and outlet, said biasing means comprising a springmember positioned within the flow passageway and acting against saidvalve member for urging it into a closed position across said inlet,adjustable means associated with said housing and extending into thepassageway at the outlet end thereof for positioning said valve memberin said passageway in opposition to said spring member, said m ans forositionin said valve member com risin an ad justable setscrew gxtendingthrough said h busin at the outlet end of said passageway into contactwith said valve member for variably positioning said valve member withinthe passageway so that the passageway between said inlet and outlet ismaintained partly open, said valve member having a surface adjacent theoutlet end of said flow passageway on which the fluid medium acts fordisplacing said valve member against the biasing action of said springmember for increasing the opening of the passageway between the inletand outlet as the pressure of the fluid medium increases.

1. A speed control valve for use in a supply line delivering a fluidmedium to a fluid driven motor which provides the input power in atorque transmission system, comprising a valve housing, said valvehousing containing an axially extending flow passageway therein with asingle inlet communicating directly into the flow passageway and asingle outlet located at one end of and connected directly to said flowpassageway, said outlet being spaced in the axial direction of the flowpassageway from said inlet, said flow passageway arranged to afford adirect flow of the fluid medium between said inlet and outlet, anaxially extending valve member movably positioned within the passagewayin said housing and extending therein between said inlet and outlet,means for biasing said valve member in the axial direction through theflow passageway toward said outlet into a position for closing the flowpassageway between the inlet and outlet, said biasing means comprising aspring member positioned within the flow passageway anD acting againstsaid valve member for urging it into a closed position across saidinlet, adjustable means associated with said housing and extending intothe passageway at the outlet end thereof for positioning said valvemember in said passageway in opposition to said spring member, saidmeans for positioning said valve member comprising an adjustablesetscrew extending through said housing at the outlet end of saidpassageway into contact with said valve member for variably positioningsaid valve member within the passageway so that the passageway betweensaid inlet and outlet is maintained partly open, said valve memberhaving a surface adjacent the outlet end of said flow passageway onwhich the fluid medium acts for displacing said valve member against thebiasing action of said spring member for increasing the opening of thepassageway between the inlet and outlet as the pressure of the fluidmedium increases.